The present invention relates to duplicating machines, particularly to portions thereof related to cleaning an image transfer drum and moving particulate material cleaned from the transfer drum into a cleaning station.
In duplicating machines, particularly those of the electrostatic copier type, image forming toner is removed from a rotatable photoconductor drum or a reciprocating photoconductor sheet after an image transfer. Various geometric arrangements have been proposed, and any geometric arrangement for separating the cleaning station from an image forming and transferring station of the machine can be practiced with the present invention.
Such cleaning stations have employed fiber brushes which are in cleansing contact with a photoconductor drum. The cleaning brush rotates synchronously with the photoconductor drum to clean the toner and other particulate matter from the drum in preparation for receiving a new image to be reproduced. The removed material is entrained in air and passes by an electrically charged scavanger roll. The charge of the entrained particulate matter is opposite to that of the roll; hence, the scavanger roll attracts a good share of such toner particulate matter. A doctor bar or other form of scraping bar removes the particulate matter from the scavanger roll from whence it is returned to a reservoir for reuse. Also, many of the electrostatic copiers include a filter for removing nontoner particulate matter from the copier. This not only keeps the photoconductor drum clean, but also prevents such particulate matter from contaminating the toner.
One of the problems in such cleaning apparatus is that the cleansing actions become less effective as the fiber brush wears. Such wear is believed caused by impact of the brush with a knock-off bar. The knock-off bar removes the toner and other particles from the brush, allowing them to be swept past the scavanger roll.